Nurmagomedov, who retired from the UFC after the defence of his 155lbs title, had historically struggled to stay within the lightweight limit.
When weighing in for the bout last October, he had to remove his clothes behind a towel to stay under 155lbs but some critics claimed the scale was not properly set and that Nurmagomedov jumped off before the result could be properly recorded.
Nurmagomedov won the fight in the third round and pledged not to fight in the UFC again, although he is expected to hold talks this week with the organisation's president, Dana White.
McGregor, who is currently training for his rematch with Dustin Poirier, goaded Nurmagomedv in a recent interview and questioned the Russian's weight.
"He's looking like an elephant, he's looking like a little fat elephant," he told The MacLife.
"He's enjoying himself, I don't think he made weight the last time either, I was very sceptical, it was very unusual behaviour."